Key points

Give the trees a zone of their own, never the lawn's, so they can be watered deeply and less often.
Water where the feeding roots are, under the canopy and past its edge, never at the trunk.
Water a new tree often, over its root ball, then move the water outward as it grows.
Work out each tree's litres from the weather, its plant factor and the area under its canopy.
Feel the soil before you change a run time, and learn the signs of too much and too little water.

On this page

A zone for the trees alone

A hydrozone is a group of plants with similar water needs and rooting depth, in similar sun and soil, watered together on one valve with its own run time. The idea comes from California's landscape water rules, which give trees deep roots, shrubs moderate ones and lawns shallow to moderate ones.

So trees need their own zone. On the lawn's zone they get short, frequent watering: the University of Florida's extension service, UF/IFAS, finds trees and shrubs on a lawn zone are commonly over-watered, and roots kept wet for long lose their air, die back and decay.

Hunter's tree brochure agrees, and gives bubblers and drip separate zones too.

Home garden and lawn irrigation Estate and commercial landscape irrigation

Sources: California Code of Regulations, Title 23, section 490.2 (2025), Model Water Efficient Landscape Ordinance: definitions of hydrozone and plant factor; UF/IFAS Extension, University of Florida (checked 2026), Fertilization and Irrigation Needs for Florida Lawns and Landscapes (ENH860): establishment of trees and shrubs; Hunter Industries (2025), Irrigating Trees: best practices brochure (HI-042), page 4.

Where a tree drinks

The roots that take up water are not at the trunk. K-State Research and Extension finds the feeding roots of an established tree reach well beyond the edge of its canopy, most in the top 30 cm of soil, and advises against watering at the trunk. UF/IFAS puts most of a tree's roots in the top 60 cm.

Tree-care guides call the canopy's edge the drip line, as rain drips off the outer leaves there; it is not the dripline pipe below. Wet the soil under the canopy and past its edge, and keep the trunk dry: Hunter aims bubblers away from the base of the tree to prevent root rot.

Edge of the canopy: tree-care guides call it the drip line, where rain drips off the outer leaves
Feeding roots: most lie in the top layer of soil and reach well past the canopy's edge
Trunk: kept dry, with no water at its base
First ring of drip, near the root ball, where a newly planted tree drinks
Second ring, under the canopy's edge, added as the tree grew
The rings from above, with the next ring, dashed, to add as the canopy spreads

Feeding roots spread wide and shallow, past the canopy's edge. Rings of drip water them, away from the trunk; the next ring goes further out.

Sources: K-State Research and Extension (2008), Watering Established Trees and Shrubs (MF2801); UF/IFAS Extension, University of Florida (2020), How Much Space Does My Shade Tree Need? (ENH1328); Hunter Industries (2025), Irrigating Trees: best practices brochure (HI-042), page 2.

Trees in the zone

A 2017 survey of Abuja's city trees counted gmelina (Gmelina arborea), black afara (Terminalia ivorensis), flamboyant (Delonix regia), Indian almond (Terminalia catappa), dry-zone mahogany (Khaya senegalensis) and the masquerade tree (Polyalthia longifolia) among the most numerous, with fewer mango (Mangifera indica) and neem (Azadirachta indica). It counted royal palms as well, which our palm guide covers.

UF/IFAS's fact sheets describe three of them, below: all want full sun and grow about as wide as they are tall, or wider. Sizes are for Florida, converted from feet.

Tree	Height when grown	Canopy spread	Drought tolerance
Flamboyant (Delonix regia)	11 to 12 m	12 to 18 m	High: water it well until established, then only in severe droughts
Indian almond (Terminalia catappa)	9 to 17 m	9 to 15 m	High
Mango (Mangifera indica)	9 to 18 m	9 to 15 m	Moderate: it wants ample moisture

Watering palms: how much, how often and with what

Sources: Agbelade, Onyekwelu and Oyun (2017), Tree species richness, diversity and vegetation index for Federal Capital Territory, Abuja, Nigeria, International Journal of Forestry Research: Table 2; Anigboro and others (2018), Phytochemical constituents, antidiabetic and ameliorative effects of Polyalthia longifiola leaf extract in alloxan-induced diabetic rats, Journal of Applied Sciences and Environmental Management 22(6): introduction, the tree's name in Nigeria; UF/IFAS Extension, University of Florida (checked 2026), Delonix regia: Royal Poinciana (ENH387); UF/IFAS Extension, University of Florida (checked 2026), Terminalia catappa: West Indian-Almond (ENH-784); UF/IFAS Extension, University of Florida (checked 2026), Mangifera indica: Mango (ENH563).

Bubblers or rings of drip

Hunter's tree brochure waters trees over the roots and away from the trunk; this guide uses two of its ways.

Bubblers suit new trees, and small to medium ones, in light to medium soils. A bubbler is a nozzle that floods a small area, here over the roots. Hunter's PCN bubbler nozzles screw onto a Pro-Spray pop-up body and give 0.9 to 7.6 litres a minute, by model. They are pressure-compensating: each gives the same flow over a wide range of pressures.

Rings of dripline suit trees of all sizes, and medium to heavy soils such as clay. Dripline is pipe with drippers built in; Hunter's HDL-PC has drippers of 2.4 or 3.8 L/h, 30 or 45 cm apart, laid under mulch or up to 5 cm into the soil.

Start over the root ball and move outward as the roots spread: larger nozzles in the same bodies, or MP Rotator nozzles for large trees, aimed away from the trunk; or, as Hunter's drip guide shows, more rings within the canopy's expected spread.

The zone has its own valve. Drip also needs a filter and a pressure regulator after the valve (Hunter's HFR filter regulator does both), a flush valve at the end of the rings and an air relief valve at their highest point.

Hunter PCN bubbler nozzle, which fits a Pro-Spray body Hunter Pro-Spray pop-up body Hunter HDL-PC dripline Hunter PLD dripline fittings Hunter filter regulator Hunter PGV zone valve Hunter MP Rotator nozzle Drip tape or dripline: how dripline works

Sources: Hunter Industries (2025), Irrigating Trees: best practices brochure (HI-042), pages 2 to 4; Hunter Industries (2015), Drip Irrigation Design and Installation Guide (LIT-496), page 19; Hunter Industries (2026), Product Catalogue Vol. 41, EMEA metric edition, pages 81, 169 and 172.

How much water, and for how long

A tree's daily water need, in mm, is ETo × plant factor. ETo is the weather's drying power: the water a well-watered field of grass would lose in your weather, in mm a day, as our crop guide explains.

The plant factor scales ETo to the plant. California's rules class it as very low, below 0.1; low, 0.1 to 0.3; moderate, 0.4 to 0.6; or high, 0.7 to 1.0, drawing on WUCOLS, a Californian plant list. WUCOLS rates the flamboyant, the neem and the African tulip tree (Spathodea campanulata) moderate wherever it rates them, so treat a tree zone as moderate. The classes are Californian and a guide only: watch your trees and adjust.

For one tree, multiply by the circle under its canopy, since 1 mm of water over 1 m² is 1 litre, and divide by 0.9: drip gets about 90 percent of the water to the roots, FAO's value, which this series uses for bubblers too.

Worked example, for illustration only

A grown shade tree on two rings of dripline, in a dry month

Assumptions

ETo of 6 mm a day, this series' figure for a dry-season month in the north and centre: monthly averages at Afaka, Kaduna State, were about 5.5 to 6.6 mm a day from December to March, and FAO gives 6 to 7 mm a day for a semi-arid area at 15 to 25°C. The south and the rainy season run lower.
Plant factor 0.5, picked from the moderate class (0.4 to 0.6) for the example.
A canopy 6 m across: a circle of 3.14 × 3 × 3 = 28 m².
Two rings of Hunter HDL-PC dripline, 1.5 m and 3 m from the trunk, with 2.4 L/h drippers every 30 cm.
About 90 percent of the water reaches the roots, FAO's value for drip.
Loam, watered deeply once a week: the frequent end of what Nebraska Forest Service advises for established trees in a severe drought.

Working

Need: 6 × 0.5 = 3 mm a day, and 3 × 28 = 84 litres a day.
With losses: 84 ÷ 0.9 = 93 litres a day, or 93 × 7 = 651 litres a week.
Rings: 2 × 3.14 × 1.5 = 9.4 m and 2 × 3.14 × 3 = 18.8 m, together 28.2 m, or 28.2 ÷ 0.3 = 94 drippers.
Flow: 94 × 2.4 = 226 litres an hour.
Run time: 651 ÷ 226 = 2.9 hours a week.

Result: In this example the rings run just under 3 hours, once a week. On sand, which Hunter's guide waters on more days, give the same water as two runs of about 90 minutes, three or four days apart; on clay, split each run into cycles with pauses. Where several trees share the zone, size each tree's rings to its canopy, so one run time suits all.

How ETo is worked out, in our crop guide Watering sandy, loamy and clay soils

Sources: Onwuegbunam and others (2025), Actual crop coefficients and yield response factors of irrigated tomato in Afaka, Northwest Nigeria, Journal of Applied Life Sciences and Environment 58(1): study location and Tables 1a and 1b; FAO (1986), Irrigation Water Management Training Manual No. 3: Irrigation Water Needs, chapter 3, Tables 5, 6 and 14; California Code of Regulations, Title 23, section 490.2 (2025), Model Water Efficient Landscape Ordinance: definitions of hydrozone and plant factor; University of California, Davis (2025), WUCOLS V: Water Use Classification of Landscape Species, ratings by region; FAO (1989), Irrigation Water Management Training Manual No. 4: Irrigation Scheduling, Annex I, Table 8; Hunter Industries (2026), Product Catalogue Vol. 41, EMEA metric edition, page 172; Nebraska Forest Service, University of Nebraska-Lincoln (checked 2026), When to water trees; Hunter Industries (2019), Residential Sprinkler System Design and Installation Guide (LIT-226), page 26.

Settling a new tree in

A new tree drinks only from its root ball until its roots grow out, which takes about 6 to 12 months for container trees in Florida, UF/IFAS finds. Until then, water the root ball, never the trunk.

UF/IFAS's schedule for strong growth in Florida is below; trees watered only two or three times a week survive, but take much longer to establish. For each watering on that lighter schedule it gives 2 to 3 US gallons per inch of trunk diameter, about 3 to 4.5 litres per centimetre, soaked into the root ball, and none if the root ball is still wet. In Florida's warmest parts, a tree takes about 3 months to establish for every inch, or 2.5 cm, of trunk.

Trunk diameter at planting	Every day for	Then every other day for	Then
Under 5 cm	2 weeks	2 months	Weekly until established
5 to 10 cm	1 month	3 months	Weekly until established
Over 10 cm	6 weeks	5 months	Weekly until established

Worked example, for illustration only

A new tree with a 4 cm trunk, on two bubblers

Assumptions

A trunk 4 cm across, so the first row of UF/IFAS's Florida schedule applies, with about 3 months to establish for every 2.5 cm of trunk, its figure for Florida's warmest parts.
3 to 4.5 litres per centimetre of trunk at each watering: UF/IFAS's amount for its lighter schedule, used here on the schedule for strong growth.
Two Hunter PCN-25 bubbler nozzles on the root ball, clear of the trunk, at 0.9 litres a minute each.

Working

Each watering: 4 × 3 = 12 litres to 4 × 4.5 = 18 litres.
The two bubblers give 2 × 0.9 = 1.8 litres a minute, so they run 12 ÷ 1.8 = 7 minutes to 18 ÷ 1.8 = 10 minutes.
Establishing: 4 ÷ 2.5 × 3 = about 5 months.

Result: In this example the bubblers run 7 to 10 minutes: every day for 2 weeks, every other day for 2 months, then weekly until the tree is established, about 5 months after planting.

Sources: UF/IFAS Extension, University of Florida (checked 2026), Fertilization and Irrigation Needs for Florida Lawns and Landscapes (ENH860): Table 1 and its notes; Hunter Industries (2026), Product Catalogue Vol. 41, EMEA metric edition, page 81.

Grown trees through the year

Once established, water deeply and less often, as Hunter's design guide says of established plants; Nebraska Forest Service advises soaking the soil 20 to 30 cm deep or more. Keep mulch over the roots, never piled against the trunk.

Need climbs through the dry season: FAO puts the highest needs where it is hot, dry, windy and sunny. In the north the dusty harmattan may blow from October to May, and at Afaka, Kaduna State, ETo peaked in March.

If water runs short in the dry season, Nebraska Forest Service puts young and newly planted trees first, and trees before grass, which is far easier to replace than trees that have grown for years.

When the rains come, cut the zone back or switch it off, and top up only in dry spells. UF/IFAS warns that a young tree watered only to survive may need water through the hot, dry season of the year after planting.

Planning dry-season irrigation in Nigeria Supplemental irrigation in the rainy season

Sources: Hunter Industries (2019), Residential Sprinkler System Design and Installation Guide (LIT-226), page 26; Nebraska Forest Service, University of Nebraska-Lincoln (checked 2026), When to water trees; K-State Research and Extension (2008), Watering Established Trees and Shrubs (MF2801); FAO (1986), Irrigation Water Management Training Manual No. 3: Irrigation Water Needs, chapter 2, section 2.1 and Table 1; FAO (1994), Aquatic plants and wetland wildlife resources of Nigeria, CIFA Occasional Paper 21: section 1.1, Climate; Onwuegbunam and others (2025), Actual crop coefficients and yield response factors of irrigated tomato in Afaka, Northwest Nigeria, Journal of Applied Life Sciences and Environment 58(1): study location and Tables 1a and 1b; UF/IFAS Extension, University of Florida (checked 2026), Fertilization and Irrigation Needs for Florida Lawns and Landscapes (ENH860): Table 1, note 3.

Signs and checks

Watch the leaves, but check the soil before you change a run time:

Too little water: leaves droop, yellow, wilt or drop early, and their edges turn brown (UC IPM).
Too much water: wet soil shuts out the air roots need, and root and crown rots follow; UC IPM names water at the base of the trunk as a main cause.
A day after watering, feel the soil at the canopy's edge with the feel test in our soils guide: it should be moist through the top layer.
Keep water and mulch off the trunk.
Each dry season, check that the outer ring still reaches the canopy's edge; add a ring when it does not.
At the start of each dry season, flush the rings, clean the filter, and note the pressure at the valve and the flush valve against last season's.

Irrigation maintenance through the season The feel test, in our soils guide

Sources: UC IPM, University of California (checked 2026), Water management and pest problems; Nebraska Forest Service, University of Nebraska-Lincoln (checked 2026), When to water trees; Hunter Industries (2015), Drip Irrigation Design and Installation Guide (LIT-496), pages 19 and 24; Hunter Industries (2019), Residential Sprinkler System Design and Installation Guide (LIT-226), page 26.

When to ask for a design

A tree zone's sizes depend on the site: the water source's flow and pressure, the slope, the soil, and how many trees there are and how big they will grow. Size the pipes and valve for the rings to come.

To design it, we need:

State and town or local government area
Crop, or the type of site
Area, in hectares, acres or square metres
Where the water comes from, and how much you think you have
How you pump today, and what powers the pump
When you want the system working
How many trees, which kinds, how big, and which are newly planted, or photos

Trademarks belong to their owners. ASFA IRRIGATION NG LIMITED is an independent company; no partnership is implied.

Landscape irrigation Garden products in the store Request a quote

Next step

Planning water for your trees?

Tell us how many trees you have, how big they are and where your water comes from. We design and supply tree zones, and installation can be quoted.

Request a quote Start on WhatsApp

Watering trees: bubblers, drip rings and the root zone.